Mine and like electric bell



.l. B. EDER.

MINE AND LIKE ELECTRIC BELL. APPLICATION FILED FEB. 1a, 1918.

Patented Feb. 7, 1922.

1 2e 1% o H 12 j R 8 go 2 6 z: '5 l3 \Tosef' Bernhard [Her 87 W WW ATTY,

UNITED STATES PATENT OFFICE.

MINE AND LIKE ELECTRIC BELL.

' To all whom it may concern:

gong o.

Be it known that J osnr BERNHARD Ennn, electrical engineer, residing at 28 Nellie Road, Norwood, Johannesburg, Transvaal, Union of South Africa, a British sub ect, has inventedcertain new and useful Improvements in Mine and like Electric Bells, of

which the following is a specification. 7

The present invention has reference to electric bells such as are employed for mine signaling, havinga-magnet within the cas ing, an armature within the cas ng and fast to a rocking spindle which extends outside the casing and a hammer secured to the spindle'outside thecasing and arranged to strike a gong which overhangs the hammer and the casing.

The invention consists inthe improved construction of such a bell as hereafter defined, the organization being such that the dome-shaped gong protects the casing from dropping moisture, while the hammer is adapted to swing between the wall of the casing and the gong and to impart its stroke to the gong in such a manner that the full volume of sound will be obtained.

In the accompanying drawings Fig. I IS an elevation partly sectioned and with the magnet removed, and Fig. II is a plan with the gong and cover removed.

1 is a hollow, cylindrical casing mounted on a base 2. At the top it is-fitted with a cover 3 on which is a post 4 carrying the The latter is of the usual dome shape and overhangs the casing and the hammer hereinafter described.

Within the casing is the bell actuating mechanism including the electro-magnet 6 and the vibrating armature 7. 8, 8 are leads connected to terminals 9 which are mounted in an insulating block 10 secured beneath the base.

The current passes by way of the contact screw 25 to a contact spring 26 mounted on and insulated from the armature 7; and thence by a direct flexible connection 27 to the windings of the coil 6. y

The armature 7 is rigidly secured to a vertical spindle 11 pivoted at its lower end in the bottom of the casing, but not passing through the same, and is'journalled adjacent its upper end in a bracket 12 detachably secured to the upper flange 13 of the casing. It is formed with a collar 14 which engages the bracket to prevent the spindle from rising.

Specif cation of Letters Patent.

Patented Feb. 7, 192 2.

ia n a tio filed February is, 1918. Serial No. 217,813..

, The bracket 12 is formed with a flange 15.

which constitutes a continuation of the flange 13 and with which the cover 3 makes joint. The cover can be removed for inspection of the interior of the casing without interfer ing with the bell striking mechanism.

The spindle 11 projects above the bracket '12 and cover 3, and to it the boss 16 ofthe hammer stem 17 is detachably but rigidly secured by the set screw 18. r

The stem is as usual curved about half way round the outside of the casing 1 and carries the head 19 which impinges on the lug 2O inside the gong. The armature, spindle and hammer being rigid with, one another, vibration of the armature causes the hammer to strike the gong. Since this method of mounting the parts permits free movement of the hammer, it is possible to obtain a satisfactorily long stroke and loud tone from the bell.

The armature and hammer are retracted by a fiat and wide spring 21 which is rigidly secured to the spindle 11 and extends substantially at right angles to the armature 7, so that when bent into position it bears against the side of the casing. Said spring curves around the interior of the casing and occupies very little space. It can be made of ample power and deteriorates very little.

with use.

It is usually desirable to prevent'the entrance of moisture around the spindle and for this purpose the under surface of the boss 16 is formed with an annular groove in which a packing ring 22 is placed.

The construction shown permits any movement of the armature 7 to be freely transmitted to the hammer 17; and in order to afford ample space for the movement of the armature, the electro-magnet is formed with a single coil 6. This encloses a core, not shown, having a pole piece 23 at each end. On the pole pieces are pole faces 24 arranged at the side of the coil. The armature is arranged parallel with the coil 6 to co-act with the pole faces. This single pole construction makes it possible to obtain a highmagnetic flux for the space occupied by the magnet, whilst. the right angle form of the unit comprising the armature 7, the spindle 11 and the spring 21, conforms satisfactorily with the magnet to produce a construction in which the limited space available within the casing is utilized to the best advantage.

As illustrated in Fig. 1, the dome-shaped gong is of considerably larger diameter than the casingand extends downward to approximately midvvay of the height of the casing. By reason of this construction, the dome serves the double purpose of forming an umbrella for the protection of the casing from dropping moisture and permitting the hammer to have a long swing so as to strike the gong a relatively hard blow. Moreover, it Will be observed that because of the fact that the stroke of the hammer is transmitted to the gong through the lug 20 at the extreme edge of the gong, the sound is considerably intensified.

I claim 1. In an electric bell, the combination with a water-tight casing enclosing the bell-operating mechanism including a pivotally mounted armature, of a dome-shaped gong mounted centrally at the top of the casing, said gong being of larger diameter than the casing and overhanging the latter, the pivot of the armature extending through the "top of the casing, a hammer adapted to swing between the'wall of the casing and the gong, a lug projectingfrom the gong into the path of the hammer to receive the stroke thereof,

and means for securing the hammer to the armature pivot above the casing.

2. In an electric bell, the combination With a Water-tight casingenclosing thebell-op erating mechanism: including a pivotally,

mounted armature,ol a dome-shaped gong mounted centrally at the top of the casing, said gong being of larger diameter than the "casin and overhan in the latter, to a)- g c: a: l

proximately midway of its height,-the pivot of the armature extending through the top" Josnr BERNHARD EDER- 

